The present invention relates generally to systems and methods for generating electrical power. More particularly, this invention pertains to a system and method of generating power using one or more flywheels.
Power generation systems are known in the art. For example, U.S. Pat. No. 2,688,704 teaches a conventional power generation system that includes a motor that is directly connected to a generator. The motor is powered by an ac power source and is used to drive the generator at its designed operating speed. The generator, in turn, generates power based on the speed at which the motor drives the generator. The system also includes a flywheel, clutch, and combustion engine, all of which are connected to the generator. If power to the motor is interrupted, the clutch engages and the flywheel, which is rotating at the designed operating speed of the generator and contains a certain amount of kinetic energy, is used to supply power to and start the combustion engine. The combustion engine is then used to drive the generator at its designed operating speed.
The system described in the '704 patent has several disadvantages. First, directly coupling the motor to the generator as taught by the '704 patent increases the overall cost of the system. As a result of the direct coupling, the motor must be capable of supplying the starting and peak load torques for the generator, both of which are greater, and, in some cases, substantially greater, than the typical operating torque required to operate the generator at its designed operating speed and only occur during relatively small portions of the overall operating time of the generator. The generator starting torque is the torque required to start the generator, the peak load torque is the torque required to handle the peak load on the generator, and the operating torque is the torque required to maintain the generator at its designed operating speed. More importantly, these torque requirements require the selection of a motor capable of supplying the higher starting and peak load torques rather than a motor capable of supplying the lower generator operating torque. Motors capable of supplying the starting and peak load torques are more expensive than motors capable of supplying the generator operating torque.
Second, the system in the '704 patent will fail if the generator creates a load on the motor that exceeds the motor's torque output capacity. In some applications, it is difficult to accurately determine the maximum torque that will be required by a system and, as a result, it is difficult to select the correct motor for those applications. While this issue is normally dealt with by building in a safety factor and selecting a motor that has a torque output capacity a certain percentage higher, for example, 20% or 30%, than any expected torque requirements, it is possible that the safety factor can be exceeded. If the safety factor is exceeded, i.e., the torque output capability of the motor is exceeded, the motor will fail and systems that are connected to the generator and relying on its power output will be unable to operate properly. Furthermore, selecting a motor with a built in safety factor requires the selection of a motor having a higher torque capability than required for a particular application and, as indicated above, increases the overall cost the system.
What is needed, then, is a less expensive power generation system having a motor generator combination that will not fail if the generator requires torques, including starting and peak load torques, that exceed the torque output capabilities of the motor.